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1-2 Identifying Minerals
1. Classify Minerals using common mineral identification
techniques.
2. Explain special properties of minerals.
Color
• Color is not the best factor to use in identifying a mineral.
• Impurities and weathering cause minerals to come in different colors.
Luster – The way lights reflects off a mineral’s surface.
• Metallic – shiny like metal
• Sub-metallic – shiny but not smooth looking.
• Non-metallic – vitreous, silky, resinous, waxy, pearly, and earthy.
Streak – the color of a mineral in powdered form.
• Rub a mineral against an unglazed porcelain tile (streak plate)
• Streak color is a more reliable way to use color in identifying a mineral in some cases.
Cleavage Vs Fracture
• Cleavage is the tendency for some minerals to break along flat surfaces.
• Fracture is the tendency for some minerals to break unevenly along curved or irregular surfaces.
Hardness – a mineral’s resistance to being scratched.
• Use Moh’s hardness scale where 1 is softest and 10 is hardest.
Density – The measure of how much matter there is in a given amount of space.
• D = m/v• Water is 1g/cm3
• Specific gravity – the ratio of a mineral’s density to water’s
• Gold is 19
Special Properties
• Fluorescence – minerals glow under a black light.
• Chemical Reaction – reacts with acid
• Optical properties – when looking through a mineral the appearance changes
• Taste – mineral has a distinctive taste.
• Magnetism – mineral will attract iron objects.
• Radioactivity – minerals that contain uranium or radium can be detected with a Geiger counter
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